5 ms·

Alternatively: "how human beings rose from the lesser hominids in 70,000 B.C.E." There's a serious theory it was this bottleneck where humans were confined to

by kobeya 9y ago

Alternatively: "how human beings rose from the lesser hominids in 70,000 B.C.E." There's a serious theory it was this bottleneck where humans were confined to environments without natural preditors (seaside cliffs like those near Cape Town) and where social interaction was a necessity. Those with higher intelligence, particularly social intelligence, would scored more mates in that environment. And thus we had a runaway intelligence arms race that separated modern humans from their immediate hominid ancestors.

bradneuberg 9y ago
Interesting theory! Do you have a link or reference where that theory is expanded more?
canjobear 9y ago
Why would a lack of natural predators make social interaction necessary?
- analog31 9y ago
  Perhaps the confinement was the part that made social interaction necessary, if humans were stuck sharing a small area rather than expanding into the neighboring territory.
- kobeya 9y ago
  It makes evolutionary selection be due to internal social/tribal pressures rather than a predator-prey interspecies relationship.
  - TheOtherHobbes 9y ago
    If you think about it, it doesn't - at least not on an individual level. I suspect it's more likely that the selection happened between tribal groups, not within them. Given independent groups with similar challenges, some would have the intelligence and luck to survive, and some wouldn't. After a challenging event like Toba, tribes/herds with a culture that couldn't adapt or survive would be culled fairly quickly.
    - coldtea 9y ago
      >If you think about it, it doesn't - at least not on an individual level. Selection doesn't work on the individual level.
saalweachter 9y ago
Note that humans and Neanderthals diverged 400,000 years ago, and when they died out ~40,000 years ago, they were basically technologically and socially indistinguishable from humans. So I'm doubtful the secret sauce of humans had its origin 70,000 years ago.
- malloryerik 9y ago
  They were humans, right? Just not homo sapiens. Human is the genus, not the species?
  - crowbahr 9y ago
    Correct. Also they are still in our genome to varying degrees.
    - saalweachter 9y ago
      Yeah, that comment started out as "anatomically modern humans" with a caveat on later interbreeding before editing; I hope the elisions were a net gain for getting the point across, if slightly less precise.
  - dalbasal 9y ago
    Yes. But species are to some extent artificial categories. Sapiens and Neanderthals were close. Genetically compatible and behaviorally similar (as far as we can tell). It would not be unreasonable to define them all as subspecies or ever varieties within a species.
    - Mayzie 9y ago
      Like dogs!
    - danieltillett 9y ago
      Apart from the minor fact that until we knew some of us are descended from Neanderthal they were consider by everyone to be different species. Ideology 1, science 0.
adrianratnapala 9y ago
Certainly the game of getting smarter due to sociality had been going on for a long time before this. But it is still quite possible that something about those survivors gave them an edge in the following centuries. And since we can't see a fast change in anatomy around then, it is a fair guess that any such change was mental.
dalbasal 9y ago
I don't think these are necessarily incompatible theories. First, any theories about this period (the paleo revolution and/or dispersal era in a lot of theories) are very speculative and prone to change. We just don't have that much information. So, the margins are necessarily huge. So, both these bottleneck narratives are probably over-literal reading of the data we have, at least stated in simple forms. Either way, they point to a single small seed population. There could have been many times more people (neanderthals and sapiens) at the time and later, and they just passed on far fewer genes to 100ky later. Yuval Harari touches on the question you raise. Sapiens vs neanderthal (and others), and at one point do human behavioural characteristics (or more precisely their consequences) emerge as different. His take is (roughly): [1] "anatomically modern" sapiens existed for 100ky+ before these behaviours emerge. [2]Findings do not imply a big cognitive or behavioural gap between sapiens and earlier subspecies in this period. [3] there appear to be botlenecks in our lineage, dating to this period [4] The "paleo-revolution" happened in some form, and he believes it was primarily linguistic [5] Our language abilities allow flexible, large scale cooperation that is unrivaled in our clade, and did not widely exist in the lower paleolithic even in sapiens [6] he spends a lot of time on the nature of those linguistic tools. In a nutshell, advanced language allows symbolism, necessary for human-level culture. Trade. Chiefs. Tribes. Gods. Money. All that could have happened in a single cliffside cove. That seems possible. His argument/theory is attractive, but these things are far from set in stone. New findings will force all theories to adapt. Some will become unlikely.
saladeen 9y ago
That is easily disproved: Khoisan people are the earliest offshoot off the sapiens evolutionary tree - they split from the rest of us cca 175 thousand years ago, and they are behaviouraly modern in all possible ways - they have large social groups, language, culture etc, which indicates those characteristics were already evolved by 175kya.

by kobeya 9y ago

bradneuberg 9y ago

Interesting theory! Do you have a link or reference where that theory is expanded more?

canjobear 9y ago

Why would a lack of natural predators make social interaction necessary?

analog31 9y ago
Perhaps the confinement was the part that made social interaction necessary, if humans were stuck sharing a small area rather than expanding into the neighboring territory.
kobeya 9y ago
It makes evolutionary selection be due to internal social/tribal pressures rather than a predator-prey interspecies relationship.
- TheOtherHobbes 9y ago
  If you think about it, it doesn't - at least not on an individual level. I suspect it's more likely that the selection happened between tribal groups, not within them. Given independent groups with similar challenges, some would have the intelligence and luck to survive, and some wouldn't. After a challenging event like Toba, tribes/herds with a culture that couldn't adapt or survive would be culled fairly quickly.
  - coldtea 9y ago
    >If you think about it, it doesn't - at least not on an individual level. Selection doesn't work on the individual level.

saalweachter 9y ago

Note that humans and Neanderthals diverged 400,000 years ago, and when they died out ~40,000 years ago, they were basically technologically and socially indistinguishable from humans. So I'm doubtful the secret sauce of humans had its origin 70,000 years ago.

malloryerik 9y ago
They were humans, right? Just not homo sapiens. Human is the genus, not the species?
- crowbahr 9y ago
  Correct. Also they are still in our genome to varying degrees.
  - saalweachter 9y ago
    Yeah, that comment started out as "anatomically modern humans" with a caveat on later interbreeding before editing; I hope the elisions were a net gain for getting the point across, if slightly less precise.
- dalbasal 9y ago
  Yes. But species are to some extent artificial categories. Sapiens and Neanderthals were close. Genetically compatible and behaviorally similar (as far as we can tell). It would not be unreasonable to define them all as subspecies or ever varieties within a species.
  - Mayzie 9y ago
    Like dogs!
  - danieltillett 9y ago
    Apart from the minor fact that until we knew some of us are descended from Neanderthal they were consider by everyone to be different species. Ideology 1, science 0.

adrianratnapala 9y ago

Certainly the game of getting smarter due to sociality had been going on for a long time before this. But it is still quite possible that something about those survivors gave them an edge in the following centuries. And since we can't see a fast change in anatomy around then, it is a fair guess that any such change was mental.

dalbasal 9y ago

I don't think these are necessarily incompatible theories. First, any theories about this period (the paleo revolution and/or dispersal era in a lot of theories) are very speculative and prone to change. We just don't have that much information. So, the margins are necessarily huge. So, both these bottleneck narratives are probably over-literal reading of the data we have, at least stated in simple forms. Either way, they point to a single small seed population. There could have been many times more people (neanderthals and sapiens) at the time and later, and they just passed on far fewer genes to 100ky later. Yuval Harari touches on the question you raise. Sapiens vs neanderthal (and others), and at one point do human behavioural characteristics (or more precisely their consequences) emerge as different. His take is (roughly): [1] "anatomically modern" sapiens existed for 100ky+ before these behaviours emerge. [2]Findings do not imply a big cognitive or behavioural gap between sapiens and earlier subspecies in this period. [3] there appear to be botlenecks in our lineage, dating to this period [4] The "paleo-revolution" happened in some form, and he believes it was primarily linguistic [5] Our language abilities allow flexible, large scale cooperation that is unrivaled in our clade, and did not widely exist in the lower paleolithic even in sapiens [6] he spends a lot of time on the nature of those linguistic tools. In a nutshell, advanced language allows symbolism, necessary for human-level culture. Trade. Chiefs. Tribes. Gods. Money. All that could have happened in a single cliffside cove. That seems possible. His argument/theory is attractive, but these things are far from set in stone. New findings will force all theories to adapt. Some will become unlikely.

saladeen 9y ago

That is easily disproved: Khoisan people are the earliest offshoot off the sapiens evolutionary tree - they split from the rest of us cca 175 thousand years ago, and they are behaviouraly modern in all possible ways - they have large social groups, language, culture etc, which indicates those characteristics were already evolved by 175kya.